Faced aerogel article and a molding process therefor

ABSTRACT

A molded article includes an aerogel layer and a surface layer which is vacuum formed to the aerogel layer. The aerogel layer provides the structural support for the article heretofore performed by chopped fiberglass. Do to the porosity of the aerogel layer, the vacuum is drawn directly through the aerogel layer such that the aerogel layer forms the mold for the surface layer which attaches thereto.

BACKGROUND OF THE INVENTION

The present invention relates to components molded of an aerogel and more particularly to a molding process for tubs, shower surrounds, and other plastic faced aerogel components.

Tub surrounds are positioned within a recess built around a bathtub or shower. Conventional modular tub/shower units often include a tub portion at the bottom and two or more wall portions. The whole structure is inserted into the wall recess to form a waterproof surround. The fully enclosed waterproof structure is highly advantageous in that it prevents the escape of water into the wall cavity despite the shower spraying water onto the surrounding walls.

Tub and shower surrounds are typically molded through an open mold fiberglass reinforced plastic molding system. As the open molds transit an assembly line, spray stations perform particular spraying operations. Such spray operations include a gelcoat and resin/catalyst/chopped fiberglass fixture application. The chopped fiberglass provides a support structure for the visible aesthetic surface.

Although effective, the chopped fiberglass may be a relatively heavy and low rigidity backing. Moreover, spraying operations for application of the multiple layers are being subjected to more and more inflexible environmental regulations.

Accordingly, it is desirable to provide a rigid structural assembly for backing an acrylic or other plastic faced product which eliminates the fiberglass spraying operation to provide a rigid, light weight and cost effective product.

SUMMARY OF THE INVENTION

The article according to the present invention is manufacture by a molding method in which a surface layer is vacuum formed to an aerogel layer. The aerogel layer provides the structural support heretofore performed by chopped fiberglass.

The aerogel is first formed to a desired article shape. The surface layer is then heated and located adjacent the aerogel layer prior to application of a vacuum. The vacuum is applied opposite the surface layer to draw the surface layer to the aerogel layer. Due to the porosity of the aerogel layer, the vacuum is drawn directly through the aerogel layer.

The present invention therefore provides a rigid structural assembly for backing a plastic faced product which eliminates the fiberglass spraying operation to provide a rigid, light weight and cost effective product.

BRIEF DESCRIPTION OF THE DRAWINGS

The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows:

FIG. 1 is a general perspective view a molded tub and surround according to the present invention;

FIG. 2 is an expanded sectional view of a tub portion taken along line 2-2 in FIG. 1; and

FIG. 3 is a schematic representation of the method to produce an article according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 illustrates a general perspective view of a molded tub and surround 20 which is formed of three pieces of molded plastic. A tub portion 22 receives wall portions 24 and 26 to form the combined tub and surround 20.

Referring to FIG. 2, the tub portion 22 is formed according to the present invention. Although the tub portion 22 is disclosed in the illustrated embodiment, it should be understood that any number of molded articles such as shower bases, sinks, or other plastic faced components will benefit from the present invention. Preferably, such components are bathroom type articles having a generally dish-like shape. The tub portion 22 is formed of at least two layers, an aerogel layer 24 and a surface layer 26 which is vacuum formed to the aerogel layer 24.

The aerogel layer 24 provides the structural support for the article heretofore performed by chopped fiberglass. As generally known, aerogels are solids with up to 99% porosity. Such large porosities confer a number of useful properties on aerogels, including high surface area, high rigidity, low density, low refractive index, low dielectric constant, low thermal-loss coefficient, and low sound velocity. Conventionally, aerogels are manufactured through processes whereby the liquid contained within the continuous network of pores of a gelatinous solid is replaced by air. Typically, this is achieved by supercritical solvent extraction, i.e., by placing the gel in an autoclave where the temperature and pressure is increased above the critical point of the liquid phase. Accordingly, dried gels, such as xerogels, cryogels, and aerogels will benefit from the present invention. “Aerogel” as used herein includes at least all of these synthesized gels. The surface layer 26 is preferably, a plastic or acrylic like material which is conducive to vacuum forming.

Referring to FIG. 3, a process according to the present invention is schematically illustrated. A sol material is first prepared and aged to form a gel and the gel formed into a final shape such as a tub or sink. The sol may be formed into a shape and then aged into a gel or the sol can be aged into a gel and then formed into a final shape. The formed, partially-dried material may also be formed within a cavity C such that upon further removal of the fluid portion of the partially-dried material, the material will “springback” to completely fill a cavity.

Drying may be accomplished at relatively low temperatures, or by exposure to vacuum or by a combination of low temperature and vacuum exposure. In low temperature and pressure (LTP) processing, the gel initially shrinks due to capillary stresses developed during drying, but because the gel does not react with itself in the shrunken state, it can springback at the final stage of drying as the capillary stress vanishes. If unconstrained, the springback restores the full original volume of the gel. If constrained by a cavity C formed by a mold M, the aerogel conforms to the shape of the cavity C which is preferably formed to the shape of the desired molded article (FIG. 2). The result is a cavity filled with aerogel that requires no supercritical processing and no molding or machining operations. It should be understood that supercritical drying, molding and/or other processing techniques will benefit from the present invention such that desired molded article is alternatively achieved.

As relatively uncomplicated and large shapes are contemplated for the present invention, tolerance requirements are of minimal significance. Of course, each forming method provides particular advantages and disadvantages which may suggest one method over another depending upon the desired article, e.g. a bathtub vs. a sink. Forming or the aerogel itself forms no part of the present invention and various known manufacturing techniques may be utilized in combination with the present invention.

Once the aerogel layer 24 is formed to the desired shape, the surface layer 26 is located adjacent thereto. The surface layer 26 is initially of a planar shape which may be affixed to an extended portion 28 of the formed aerogel layer 24 which is later removed or may be maintained adjacent thereto by a frame 30 or the like. The surface layer 26 is preheated or heated once locate adjacent the aerogel layer 24 prior to application of a vacuum. The vacuum is applied by a vacuum machine V located adjacent the aerogel layer 24 opposite the surface layer 26. Do to the porosity of the aerogel layer 24, the vacuum is drawn directly through the aerogel layer 26. The surface layer 26 preferably creates the top surface of a vacuum cavity such that application of a vacuum draws the surface layer 26 about the outer visible or finished surface of molded article. The aerogel layer 24, as molded in a desired article shape, further operates essentially as a mold for the surface layer 26. Additional support or mold structure need not be provided for vacuum forming the surface layer 26.

The heated surface layer 26 is drawn onto the aerogel layer 24 and adheres thereto by interaction of the heated surface layer 26 and the aerogel layer 24. Preferably, a flange area 32 of the aerogel layer 24 provides a mechanical lock which assures attachment of the surface layer 26 even after a trimming process. That is, the surface layer 26 is drawn at least partially around an undersurface (non-visible surface) of the aerogel layer 24 to lock the aerogel layer 26 within the surface layer 26. Additionally, or in the alternative, adhesives and/or other attachments may be utilized to assure attachment of the surface layer 26 to the aerogel layer 24. It should be understood that the aerogel may be alternatively be sprayed onto a mold surface and then heated to cure.

The foregoing description is exemplary rather than defined by the limitations within. Many modifications and variations of the present invention are possible in light of the above teachings. The preferred embodiments of this invention have been disclosed, however, one of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. For that reason the following claims should be studied to determine the true scope and content of this invention. 

1. A molded article comprising: a gel layer; and a surface layer vacuum formed to said gel layer.
 2. The molded article as recited in claim 1, wherein said gel layer comprises a dried aerogel layer.
 3. The molded article as recited in claim 1, wherein said gel layer comprises a xerogel layer.
 4. The molded article as recited in claim 1, wherein said gel layer comprises a cryogel layer.
 5. The molded article as recited in claim 1, wherein said gel layer comprises a supercritical dried aerogel layer.
 6. The molded article as recited in claim 1, wherein said surface layer comprises an acrylic.
 7. The molded article as recited in claim 1, wherein said surface layer comprises a plastic.
 8. The molded article as recited in claim 1, wherein said article comprises a dish shaped member.
 9. The molded article as recited in claim 8, wherein said article comprises a bathtub.
 10. The molded article as recited in claim 8, wherein said article comprises a sink.
 11. A method of molding an article comprising the steps of: (1) molding an aerogel to a desired shape; and (2) vacuum forming a surface layer to the aerogel after said step (1).
 12. A method as recited in claim 11, further comprising the step of: drying the aerogel prior to said step (2).
 13. A method as recited in claim 11, further comprising the step of: freeze-drying the aerogel prior to said step (2).
 14. A method as recited in claim 10, further comprising the step of: supercritical drying of the aerogel prior to said step (2).
 15. A method as recited in claim 10, wherein said step (2) further comprises the step of: drawing the vacuum through the aerogel.
 16. A method as recited in claim 10, wherein said step (2) further comprises the step of: drawing the vacuum through the aerogel which forms a mold for the surface layer.
 17. A molded article comprising: a first layer comprising a porosity which permits a vacuum to be drawn therethrough; and a surface layer vacuum formed to said first layer.
 18. The molded article as recited in claim 17, wherein said first layer comprises a dried aerogel layer.
 19. The molded article as recited in claim 17, wherein said surface layer comprises an acrylic.
 20. A method of molding an article comprising the steps of: (1) providing a surface layer of a desired shape; (2) applying a gel layer to the surface layer; and (3) curing the gel layer.
 21. A method as recited in claim 20, further comprising the step of: spraying the gel layer upon the surface layer. 